Pre-qualification acts as a dry run for the actual loan application process. The mortgage lender will use the details you provide about your credit, income, assets, and debts to arrive at an estimate of how much mortgage you can afford. This whole process may take only a few minutes or a few hours, at most, and it is free! These days, most sellers will not accept an offer without, at least, a pre-approval letter, so if you are serious about buying, this is the first step towards getting your new home.